The inventive concept relates to a processor apparatus, and more particularly, to a processor apparatus having a security function with respect to a debugging operation, access to a predetermined intellectual property (IP) block, and the processor apparatus itself.
In a memory device, in a processor using the memory device and in a system apparatus using the memory device, security and protection of stored data have become very important. In particular, it is increasingly important that unauthorized access to the processor itself and exposure of the processor be prevented by maintaining processor security. In a secure processor or system, one without access rights to predetermined data, or to a processor, or to a predetermined block internally included in the processor, is prevented from access.
However, such devices, and systems employing such devices, are highly vulnerable to attacks by ill-intentioned users. Such users include unspecified individuals who try to falsify or use a memory device, a processor or a system apparatus and try to prevent an authorized user access to the memory device, the processor or the system apparatus. That is, an ill-intentioned user intentionally tries to falsify data stored in the memory device, to change an operation of the processor, or to expose information or a structure of the processor.
For example, when a boundary scan method is used, data of a processor apparatus or memory device can be read, and stored data can be falsified. In the boundary scan method, all operations of the memory device may be performed by a user making one-to-one connections between test pins and pins of the memory device, and the performance of a device can be tested. The definition and detailed structure of the boundary scan method would have been obvious to one of ordinary skill in the art.
That is, an ill-intentioned user can expose and falsify data of a processor apparatus or memory device by using a boundary scan method. In this case, security of the processor apparatus or memory device can be compromised.
Another example of security exposure is the case where a debugging operation of a processor is performed using a joint test action group (JTAG) port. When processor debugging is performed, an ill-intentioned user can change an operation of the processor or can expose secure information of the processor, without the permission of an authorized user. The JTAG port refers to a port that is separately provided in the processor, for facilitating a debugging operation. The definition and detailed structure of the JTAG port would have been obvious to one of ordinary skill in the art.
Recently, in order to prevent a JTAG port from being misused, a method in which the JTAG port is permanently disabled has been suggested. However, in this case, when a problem occurs in the processor, it is impossible to perform a debugging operation to identify the defect.